Beam Suffering
2017 Update: Beam suffering is no more, a custom panhard bar solved this problem. See the detailed post here.
The Scott-Russell Link (SRL) is really getting the best of me, especially while being lowered. The rear just seems disconnected from the rest of the car, I can feel the rear also ruining the front traction.
The problem with Scott-Russell link is, when you lower the car, the roll center still remains high, seems to be as high as 12". Mike K also mentions that that link binds and causes uneven wheel rates.
I'm currently exploring these options, I have two beamed cars that I would like this done on. One will be a autocross car, thus it would need a nicer setup, while the other is just a fun daily driver thus it doesn't need as an expensive option. If I could lower the roll center in the rear on the SRL for the daily driver, it would probably be sufficient enough.
For reference Nissan SRL Travel in action:
Options:
QT Link, on a lowered car the beam seems to move to the right, this link is adjustable thus it lets you put the beam back in the center and restore the geometry.
SE-R Spec V Scott-Russel Linkage swap
Originally Posted by choaderboy2
The B15 part is much stiffer, being fabricated from stampings so that it is hollow in cross section vs a wimpy I beam like the stock B14 part, with stiffer bushing with a forged aluminum locating link vs a wimpy steel one. I think for a B14 on R compound tires, this might make a big difference. I'll know how it helps handling soon as I can get some track time.
Spec V linkage
Panhard Conversion - Panhard links are a lot simpler then even the Scott-Russell setup, but are very effective, with the conversion you would have adjustable roll center too. Unfortunately it's a bit of an intensive installation, requires lots of welding and tuning.
Moto IQ did it on their B15 Race car:
Originally Posted by MotoIQ
Worse yet the Scott-Russell linkage has a very high rear roll center. To eliminate these issues we have to get rid of the linkage entirely. We replaced the linkage with a Panhard Rod. The Panhard Rod keeps the suspension from flexing sideways at all and lowers the roll center by as much as 6” from stock.
MotoIQ's Panhard:
smokinjoe(2j-racing) did a side by side comparison on the same turn:
Without the Panhard, using the OEM SRL
With the Panhard
Watt's Link - The guys at 2JRacing decided to try to make a Watt's link for our cars. This seems to be the best option, but is also much more complex then the Panhard setup, but it seems to be well worth the trouble.
What an OEM Watt's travel looks like:
Originally Posted by Joe@2J-Racing
I have decent news and unbelievable news. The decent news is the watts link will undergo a redesign on the mounting points. Justin and I would like to make it a bolt in part. Or a partial weld in, secured with bolts. Throughout the winter we'll refine and test the watts to make it available to anyone with decent skills.
After running two sessions I pushed the car harder than I've ever pushed it before, in a on-camber 110 mph turn, probably 1.4gs. I took it flat out. And the mounting bracket pulled away from the chassis. On a first time mock up, that's to be expected.
Now for the unbelievable news. The watts is fcking ridiculous. And I dont use that term lightly. It is the best mod I've ever done since coilovers. Hands down. The car's handling goes from numb to connected. Understeer went from moderate, to ZERO. None. Zilch.
Before when I would pitch the car in a turn, the rear would raise up and the car would begin to push. With the watts the rear squats. Yea, it squats. It's the most unbelievable feeling in the world. Turn in is usually full of drama while the SRL binds up. Now its stable, predictable and connected.
I can't wait for version 2.0. I ran a 1.39.02 at Road Atlanta. That is the fastest N/A FWD. Period. We beat the competition.
Id does seem like 2JRacing guys stuck with the Panhard setup simply because it's simple and easier to do. Plus they had some issues with body flex and welds breaking on the Watt's linkage.
Originally Posted by Joe@2J-Racing
...The big problem with the watts is the roll center, and getting the bell crank low enough (below the beam). Otherwise its just another SRL with spherical bearings...
RedDragon's Watt's Linkage Install
The Scott-Russell Link (SRL) is really getting the best of me, especially while being lowered. The rear just seems disconnected from the rest of the car, I can feel the rear also ruining the front traction.
The problem with Scott-Russell link is, when you lower the car, the roll center still remains high, seems to be as high as 12". Mike K also mentions that that link binds and causes uneven wheel rates.
I'm currently exploring these options, I have two beamed cars that I would like this done on. One will be a autocross car, thus it would need a nicer setup, while the other is just a fun daily driver thus it doesn't need as an expensive option. If I could lower the roll center in the rear on the SRL for the daily driver, it would probably be sufficient enough.
For reference Nissan SRL Travel in action:
Options:
QT Link, on a lowered car the beam seems to move to the right, this link is adjustable thus it lets you put the beam back in the center and restore the geometry.
SE-R Spec V Scott-Russel Linkage swap
Originally Posted by choaderboy2The B15 part is much stiffer, being fabricated from stampings so that it is hollow in cross section vs a wimpy I beam like the stock B14 part, with stiffer bushing with a forged aluminum locating link vs a wimpy steel one. I think for a B14 on R compound tires, this might make a big difference. I'll know how it helps handling soon as I can get some track time.
Spec V linkage
Panhard Conversion - Panhard links are a lot simpler then even the Scott-Russell setup, but are very effective, with the conversion you would have adjustable roll center too. Unfortunately it's a bit of an intensive installation, requires lots of welding and tuning.
Moto IQ did it on their B15 Race car:
Originally Posted by MotoIQWorse yet the Scott-Russell linkage has a very high rear roll center. To eliminate these issues we have to get rid of the linkage entirely. We replaced the linkage with a Panhard Rod. The Panhard Rod keeps the suspension from flexing sideways at all and lowers the roll center by as much as 6” from stock.
MotoIQ's Panhard:
smokinjoe(2j-racing) did a side by side comparison on the same turn:
Without the Panhard, using the OEM SRL
With the Panhard
Watt's Link - The guys at 2JRacing decided to try to make a Watt's link for our cars. This seems to be the best option, but is also much more complex then the Panhard setup, but it seems to be well worth the trouble.
What an OEM Watt's travel looks like:
Originally Posted by Joe@2J-RacingI have decent news and unbelievable news. The decent news is the watts link will undergo a redesign on the mounting points. Justin and I would like to make it a bolt in part. Or a partial weld in, secured with bolts. Throughout the winter we'll refine and test the watts to make it available to anyone with decent skills.
After running two sessions I pushed the car harder than I've ever pushed it before, in a on-camber 110 mph turn, probably 1.4gs. I took it flat out. And the mounting bracket pulled away from the chassis. On a first time mock up, that's to be expected.
Now for the unbelievable news. The watts is fcking ridiculous. And I dont use that term lightly. It is the best mod I've ever done since coilovers. Hands down. The car's handling goes from numb to connected. Understeer went from moderate, to ZERO. None. Zilch.
Before when I would pitch the car in a turn, the rear would raise up and the car would begin to push. With the watts the rear squats. Yea, it squats. It's the most unbelievable feeling in the world. Turn in is usually full of drama while the SRL binds up. Now its stable, predictable and connected.
I can't wait for version 2.0. I ran a 1.39.02 at Road Atlanta. That is the fastest N/A FWD. Period. We beat the competition.
Id does seem like 2JRacing guys stuck with the Panhard setup simply because it's simple and easier to do. Plus they had some issues with body flex and welds breaking on the Watt's linkage.
Originally Posted by Joe@2J-Racing...The big problem with the watts is the roll center, and getting the bell crank low enough (below the beam). Otherwise its just another SRL with spherical bearings...
RedDragon's Watt's Linkage Install
Last edited by Vadim
on 2017-05-24
at 14-52-44.
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